Fragmentation dynamics of electron-impact double ionization of helium

We study the double ionization dynamics of a helium atom impacted by electrons with full-dimensional classical trajectory Monte Carlo simulation. The excess energy is chosen to cover a wide range of values from 5 e V to 1 ke V for comparative study. At the lowest excess energy, i.e., close to the double-ionization threshold, it is found that the projectile momentum is totally transferred to the recoil-ion while the residual energy is randomly partitioned among the three outgoing electrons, which are then most probably emitted with an equilateral triangle configuration. Our results agree well with experiments as compared with early quantum-mechanical calculation as well as classical simulation based on a two-dimensional Bohr's model. Furthermore, by mapping the final momentum vectors event by event into a Dalitz plot,we unambiguously demonstrate that the ergodicity has been reached and thus confirm a long-term scenario conceived by Wannier. The time scale for such few-body thermalization, from the initial nonequilibrium state to the final microcanonical distribution, is only about 100 attoseconds. Finally, we predict that, with the increase of the excess energy, the dominant emission configuration undergoes a transition from equilateral triangle to T-shape and finally to a co-linear mode. The associated signatures of such configuration transition in the electron–ion joint momentum spectrum and triple-electron angular distribution are also demonstrated.

Double Negative Left-Handed Metamaterials for Miniaturization of Rectangular Microstrip Antenna

In this paper, I have explored a significant concept for the miniaturization of microstrip patch antenna configuration by using the double negative (DNG) left-handed Metamaterials, which have dielectric permittivity and magnetic permeability both negative, simultaneously. It is achieved through the concept of phase-compensation by thin slab consist of the double positive (DPS) material, which have dielectric permittivity and magnetic permeability both positive, simultaneously and DNG metamaterials as a substrate of the microstrip patch antenna. By combining the DNG metamaterial slab with the slab made of DPS materials form a cavity resonator whose dispersion relation is independent of the sum of thickness of the slabs filling this cavity but it depends on the ratio of their thicknesses. This cavity constitutes by DPS and DNG material is used as substrate of the microstrip antennas and the DNG material slab is behave as phase compensator.

Analysis of the Focusing Characteristics of Double Negative Binary Diffractive Lens

For a compact millimeter wave imaging system it is very important to design every component into small size, for the components in a millimeter wave system are usually much larger than those in an optical imaging system due to rela-tively long wave lengths. In this paper, we suggest a kind of binary diffractive lens (BDL) designed using double nega-tive materials (DNG) as the objective lens for a millimeter wave imaging system. The DNG-BDL has not only the ad-vantage of low profile but also small f number, which will be benefit for constructing a compact millimeter wave imaging system. Several DNG-BDL are designed and analyzed using the FDTD method. The numerical results of the focal plane field of the DNG-BDL are presented, which show that the DNG-BDL with small f number has relatively better focusing characteristic than that of a double positive BDL with same f number.

Study on the relationship between syndrome characteristics degree and inflammatory factor and negative emotional scale in"double heart disease"patients with Qi stagnation blood stasis and heart gallbladder heat stagnation

Objective:To Discuss the correlation between Hypersensitivity C-reactive Protein(Hs-CRP),Total Cholesterol(TC),Triglyceride(TG),negative emotion scale and TCM syndrome scores in“Double Heart Disease”patients with Qi stagnation blood stasis and heart gallbladder heat stagnation.Method:Fifty-two patients in Western Medicine Diagnosis of Double Heart Disease,in TCM syndrome identified as Qi stagnation blood stasis Heart gallbladder heat stagnation syndrome,detects it Hs-CRP,TC,TG levels by ELISA,use TCM Syndromes Scale to evaluate TCM Syndrome,use the Pittsburgh Sleep Quality Index(PSQI)and Self-rating symptom scale(SCL-90)to assess anxiety and sleep levels,analyze the correlation between TCM syndrome scores and Hs-CRP,TC,TG level,PSQI index,SCL-90 index.Result:There was a significant positive correlation between Hs-CRP,TG level and TCM Syndrome scores(P<0.05);TC level was postively correlated with TCM Syndrome scores,but there was no statistical significance(P>0.05);There was a significant positive correlation between PSQI index,SCL-90 index and TCM Syndrome scores(P<0.05).Conclusion:In“Double Heart Disease”patients with Qi stagnation blood stasis and heart gallbladder heat stagnation,there have characteristic syndrome changes in terms of inflammatory factor level,blood lipid level and negative emotion score;Which the above indexes can reflect the severity of TCM syndromes to a certain extent and provide the basis for the effective intervention treatment of TCM.

Migration law of respirable dust on a super-long fully mechanized double-shearer working face

In order to understand the migration law of respirable dust and gain reasonable design parameters for dust control on a super-long double-shearer fully mechanized working face, this paper describes research carried out using a numerical simulation package(Fluent) based on gas-solid coupling dispersed multiphase flow model and field measurement to research different technology modes, dust distribution law at different intervals where shearers work in opposite directions on the lower 9303 face, No. 2 Jining Mine,Yankuang Coal Mining Co. Results show that the concentration of dust 3–6 m away from the shearers working in the same directions was large, while the impact area of respirable dust near the shearer increased significantly to 5–6 m with the distance between two shearers working in opposite directions.The concentration of dust on a double-shearer face was considerably higher than that of a face with one shear under the combined effect of wind speed on the face and disturbed wind around the shearer, while the dust concentration near the shearer on the return side was considerably higher than that on the inlet side. The concentration of dust on a double-shearer face along the airflow declined slowly so that dust was hard to control. Simulation results confirmed the results of field measurement, which could provide reference for dust prevention design.

英语中“否定(Negation)”的结构分析

本文通过对否定的结构和修辞等特征进行分析,从而说明否定并不相对于肯定而存在,它应是一个相对独立的语言范畴。

Reconstitution of double-negative T cells after cord blood transplantation and its predictive value for acute graft-versus-host disease

Background:With an increasing number of patients with hematological malignancies being treated with umbilical cord blood transplantation(UCBT),the correlation between immune reconstitution(IR)after UCBT and graft-versus-host disease(GVHD)has been reported successively,but reports on double-negative T(DNT)cell reconstitution and its association with acute GVHD(aGVHD)after UCBT are lacking.Methods:A population-based observational study was conducted among 131 patients with hematological malignancies who underwent single-unit UCBT as their first transplant at the Department of Hematology,the First Affiliated Hospital of USTC,between August 2018 and June 2021.IR differences were compared between the patients with and without aGVHD.Results:The absolute number of DNT cells in the healthy Chinese population was 109(70-157)/μL,accounting for 5.82(3.98-8.19)%of lymphocytes.DNT cells showed delayed recovery and could not reach their normal levels even one year after transplantation.Importantly,the absolute number and percentage of DNT cells were significantly higher in UCBT patients without aGVHD than in those with aGVHD within one year(F=4.684,P=0.039 and F=5.583,P=0.026,respectively).In addition,the number of DNT cells in the first month after transplantation decreased significantly with the degree of aGVHD increased,and faster DNT cell reconstitution in the first month after UCBT was an independent protective factor for aGVHD(HR=0.46,95%confidence interval[CI]:0.23-0.93;P=0.031).Conclusions:Compared to the number of DNT cells in Chinese healthy people,the reconstitution of DNT cells in adults with hematological malignancies after UCBT was slow.In addition,the faster reconstitution of DNT cells in the early stage after transplantation was associated with a lower incidence of aGVHD.

A NONCLASSICAL LAW OF ITERATED LOGARITHM FOR NEGATIVELY ASSOCIATED RANDOM VARIABLES

A nonclassical law of iterated logarithm that holds for a stationary negatively associated sequence of random variables with finite variance is proved in this paper. The proof is based on a Rosenthal type maximal inequality and the subsequence method.This result extends the work of Klesov,Rosalsky (2001) and Shao,Su (1999).

Two integrable generalizations of WKI and FL equations: Positive and negative flows, and conservation laws

With the aid of Lenard recursion equations, an integrable hierarchy of nonlinear evolution equations associated with a 2 × 2 matrix spectral problem is proposed, in which the first nontrivial member in the positive flows can be reduced to a new generalization of the Wadati–Konno–Ichikawa(WKI) equation. Further, a new generalization of the Fokas–Lenells(FL) equation is derived from the negative flows. Resorting to these two Lax pairs and Riccati-type equations, the infinite conservation laws of these two corresponding equations are obtained.

Equivalent electron correlations in nonsequential double ionization of noble atoms

Electron correlation is encoded directly in the distribution of the energetic electrons produced in a recollision-impact double ionization process, and varies with the laser field and the target atoms. In order to get equivalent electron correlation effects, one should enlarge the laser intensity cubically and the laser frequency linearly in proportion to the second ionization potentials of the target atoms. The physical mechanism behind the transform is to keep the ponderomotive parameter unchanged when the laser frequency is enlarged.

Simultaneous Courvoisier's and double duct signs

Presence of Courvoisier's or double duct signs in a jaundiced patient is suggestive of malignant obstruction of the pancreaticobiliary ductal system.The oncologic impact of the simultaneous occurrence of these signs on the survival of patients with periampullary cancer is unknown.We report a case of obstructive jaundice secondary to an ampullary cancer demonstrating the Courvoisier's sign on clinical examination and a double duct sign on imaging.The patient underwent a pancreaticoduodenectomy which confirmed an ampullary adenocarcinoma.

Half-lives of double β^- -decay with two neutrinos

Nuclear double β--decay with two neutrinos is an important decay mode for some unstable nuclei. Based on the available experimental data of nuclear double β--decay, we propose that there is a law between the logarithm of double β--decay half-lives and the reciprocal of the decay energy. The physics behind the law is discussed and it is found that this is associated with the universal properties of the weak interaction. This doubleβ--decay law is similar to the famous Geiger-Nuttall law of α-decay. The law is applied to predictions of the nuclear double β--decay half-lives for six even-even nuclei from Z = 84 to Z = 98 and we found that232 Th is very interesting for future experiments. The branching ratios between double β--decay and α-decay are also estimated for the six even-even nuclei and this is useful for future experimental search of new emitters of doubleβ--decay.

Relationship between the Three Laws of Dialectics of Nature and Agricultural Development

Based on the three laws of dialectics of nature-the law of unity of opposites, the law of mutual change of quality and the law of negation of negation, this paper analyzes the relationship between the three laws and agricultural development, and proposes making good use of the three laws to promote the better development of agriculture and realize agricultural modernization.

基于对数型障碍Lyapunov函数的俯仰驾驶仪设计

相控阵雷达制导拦截弹在拦截高速大机动目标时,弹体气动参数剧烈非线性变化影响控制系统对大攻角的响应效果,应设计考虑攻角指令跟踪误差约束的鲁棒自动驾驶仪控制律。基于双幂次趋近律和对数型障碍李雅普诺夫函数设计了鲁棒非线性自动驾驶仪控制律,可将攻角指令的跟踪误差快速收敛于约束范围内。通过降阶扩张状态观测器对系统中存在的气动参数不确定性和系统外部扰动进行在线估计和补偿。稳定性分析和数值仿真表明,攻角可在1 s内达到稳态且攻角响应的稳态误差<10-4°,所提出的自动驾驶仪控制律具有较强的鲁棒性,能够准确稳定地跟踪攻角指令,控制导弹产生所需过载进而精准拦截目标。

“双减”背景下校外培训机构的法治化监管

自“双减”政策出台以来,我国在义务教育阶段文化课校外培训机构监管方面取得了一定进展。但此类校外培训机构的监管仍存在各种问题,主要表现在对校外培训机构监管立法上存在欠缺、执法上监管合力不强等方面。为实现校外培训机构监管的法治化,对构建校外培训机构监管长效机制进行了研究。通过分析我国校外培训机构监管的现状,从促进监管部门有效承担监管职责、鼓励学校提升教学效果、引导家长塑造正确教育理念等方面提出了合理化建议。

基于有限时间干扰观测器的改进模型水下机器人自适应鲁棒容错控制

针对无人水下机器人(unmanned underwater vehicle,UUV)工作中存在的执行器故障,在系统不确定性与外界干扰下,提出一种基于有限时间扰动观测器(finite time disturbance observer,FTDO),并结合改进模型的自适应鲁棒容错控制方法。一方面,FTDO能在有限时间内对外界环境干扰进行估计;另一方面利用滑模控制加上径向基神经网络(radial basis function neyral network,RBF)的万能逼近特性,建立带有执行器故障的输入补偿;其中改进模型的引入解决了系统不确定性导致的输入饱和,提高了稳定性与鲁棒性;其次采用一种新型的双幂趋近律使滑模量在更短时间收敛到稳态误差界内;仿真与水池实验结果表明了所提方法相对于滑模控制有着更好的容错效果。

人为水土流失生态环境损害“一案双查”机制研究

为强化人为水土流失生态环境损害赔偿工作,进一步创新人为水土流失生态环境损害救济体系,分析了人为水土流失生态环境损害救济现状,提出了行政执法与生态环境损害赔偿的“一案双查”机制;根据行政执法与生态环境损害赔偿两者存在的补强优势与协作优势,指出“一案双查”应遵循权责一致、依法处置、协同共治的理念;通过明晰行政执法与损害赔偿主体、厘清行政执法与损害赔偿适用情景、加强行政执法与损害赔偿协同等措施,优化完善“一案双查”机制。

双重否定结构自动识别研究

双重否定结构是一种“通过两次否定表示肯定意义”的特殊结构,直接影响自然语言处理中的语义判断与情感分类。该文以“??P==>P”为标准,对现代汉语中所有的“否定词+否定词”结构进行了遍历研究,将双重否定结构按照格式分为了3大类,25小类,常用双重否定结构或构式132个。结合动词的叙实性、否定焦点、语义否定与语用否定等理论,该文归纳了双重否定结构的三大成立条件,并据此设计实现了基于规则的双重否定结构自动识别程序。程序实验的精确率为98.80%,召回率为98.90%,F1值为98.85%。同时,程序还从96281句语料中获得了8640句精确率约为99.20%的含有双重否定结构的句子,为基于统计的深度学习模型提供了语料支持。

公平而高质量的中考分流:价值向度、实践样态及路径选择

追求公平而高质量的中考分流,应坚持按教育“内适”规律、“外适”规律和“个适”规律办好人民满意的教育,用合适的高质量教育塑造合适的人,让不同的学生流向不同的高质量学校,使每个独特的天性都得到自由生长。由于各地执行标准不一及“双减”政策落实情况参差不齐,中考分流的适应性不强,成为普通高中与中等职业学校分化、中产以上家庭子女与中产以下家庭子女学业分化学业分化、优生与差生分化的“催化剂”,成为不同受教育者机会不均、地位悬殊、能力分化的“助燃剂”,成为天性教育的梗阻。坚持教育分流政策,实现公平而高质量的中考分流,必须因情、因地、因人制宜,建立普职平等的发展机制、需求导向的调节机制和减负增效的评价机制。

ON DE FINETTI'S OPTIMAL IMPULSE DIVIDEND CONTROL PROBLEM UNDER CHAPTER 11 BANKRUPTCY

Motivated by recent advances made in the study of dividend control and risk management problems involving the U.S.bankruptcy code,in this paper we follow[44]to revisit the De Finetti dividend control problem under the reorganization process and the regulator's intervention documented in U.S.Chapter 11 bankruptcy.We do this by further accommodating the fixed transaction costs on dividends to imitate the real-world procedure of dividend payments.Incorporating the fixed transaction costs transforms the targeting optimal dividend problem into an impulse control problem rather than a singular control problem,and hence computations and proofs that are distinct from[44]are needed.To account for the financial stress that is due to the more subtle concept of Chapter 11 bankruptcy,the surplus process after dividends is driven by a piece-wise spectrally negative Lévy process with endogenous regime switching.Some explicit expressions of the expected net present values under a double barrier dividend strategy,new to the literature,are established in terms of scale functions.With the help of these expressions,we are able to characterize the optimal strategy among the set of admissible double barrier dividend strategies.When the tail of the Lévy measure is log-convex,this optimal double barrier dividend strategy is then verified as the optimal dividend strategy,solving our optimal impulse control problem.